1. Field of the Invention
The present invention relates to a method for manufacturing a field emission substrate and, more particularly, to a method for manufacturing a field emission substrate that is able to reduce damage to electron emitters and easily control arrangement of the electron emitters.
2. Description of Related Art
Display devices are playing an increasingly important role in people's daily life. Computers, TVs, mobile phones, PDAs, digital cameras etc., all transmit information by controlling display devices. Contrary to the conventional Cathode Ray Tube displays, the latest-generation panel displays are advantageous in that they are light, compact, and health-friendly.
Among various technologies for panel display devices, field emission displays (FED) boast not only great graphic qualities as found in conventional Cathode Ray Tube displays, but also high luminescent efficiency, short response time, good display coordination performance, high brightness of over 1000 nits, slim and light structure, wide viewing angle, broad range of working temperature, and high acting efficiency, contrary to Liquid Crystal Displays (LCD) which are problematic in narrow viewing angle, narrow working temperature range, and short response time.
Besides, FEDs do not require backlight modules, so they can provide superior brightness even when used in sunlight. With the development of nanotechnology, materials for novel electron emission components are continuously being discovered, and this has become a significant topic in related research. The carbon nanotube field emission display devices are utilized mainly based on the principles of tip discharge of carbon nanotubes to replace prior art metal tip-emission components that are short-lived and difficult to manufacture.
The working principle of a field emission display device is similar to that of a conventional Cathode Ray Tube display device. Electrons are drawn out from the tip of the cathode in a vacuum environment by applying an electric field, accelerated by positive voltage at the anode, and impact phosphor powder on the anode plate such that luminescence is generated. Thus, distributive homogeneity of electrons is critical to uniform illumination and light.
Each pixel in the field emission display device has a corresponding field emission array, so in case that electron emitters are distributed unevenly, or areas of emission are different, non-homogenous electron emission could be resulted. Consequently, that phenomenon could cause uneven screen brightness, low contrast, and low yield rate. The image qualities are thereby affected.
In conventional low-cost screen-printing, the material must be shaped through a high-temperature sintering process, but sintered materials cannot form smooth-surface layers and collapse and deform very easily. Furthermore, sizes of the display manufactured by screen-printing are limited, so the precision is difficult to be improved.
Though photolithography is also used to precisely control the arrangement and areas of the electron emitters on the substrate, the process consumes more electron emission materials and thereby incurs higher manufacture costs. Etching and shaping the components could even cause damage to electron emitters. Ink-jet printing is also employed to manufacture electron emitters. Though the procedures are simple, ink-jet printing suffers from the problem that uniformity of thickness is not easily achieved, leading to uneven electron emission.
Therefore, there is a need to develop a method for manufacturing a field emission substrate, which allows accurate controlling distribution of electron emitters on the substrate. The process is simple and causes no harm to electron emission components, and it is possible to prepare electron emitters having uniform areas and thickness to provide homogenous electron emission, so that image qualities and yield rates are improved.